New Delhi Metallo-Beta Lactamase (NDM-1) a SuperBug

Synopsis and Key Points:

Information regarding NDM-1 an enzyme that renders bacteria resistant to several antibiotics. A sign that a person is infected with bacteria carrying NDM-1 is failure of antibiotic treatments.

Main Digest

'New Delhi Metallo-Beta-Lactamase,' or, 'NDM-1,' is the name given to an enzyme discovered in 2009 that is able to be produced by a number of genera of bacteria that render the bacteria resistant to several antibiotics in use around the world today.

An enzyme that makes bacteria resistant to a broad range of beta-lactam antibiotics. These include the antibiotics of the carbapenem family, which are a mainstay for the treatment of antibiotic-resistant bacterial infections. The NDM-1 enzyme was named after New Delhi, the capital city of India. NDM-1 was first detected in a Klebsiella pneumoniae isolate from a Swedish patient of Indian origin in 2008. In August 2010, the first reported death due to bacteria expressing the NDM-1 enzyme was recorded after a Belgian man, who had become infected while being treated in a hospital in Pakistan, died despite being administered colistin.

The enzyme belongs to a group of enzymes that are capable of breaking the chemical bonds of a beta-lactam ring, which composes an important part of many antibiotics such as drugs of the cephalosporin, penicillin, and carbapenem groups. The majority of the beta-lactamase enzymes are effective on some, or most, of the older antibiotics like cephalosporins and penicillins. NDM-1; however, is effective on both newer and older antibiotics that contain a beta-lactam ring.

'Klebsiella,' were the first bacteria identified in 2009 to produce NDM-1 in a person who traveled from India to England with an infection that failed to respond to several antibiotics. The organism was resistant to beta-lactams and after the organism's genetic and antibiotic resistance mechanisms were studied - NDM-1 and its genetic source were discovered. The genetic source was a plasmid termed, 'blaNDM-1,' and since the time of its discovery, additional bacterial genera have been found to have blaNDM-1 integrated into other plasmids, or into the bacterial chromosome, permitting the bacteria to produce NDM-1.

While NDM-1 is effective against nearly every antibiotic with a beta lactam ring, it is not effective in producing antibiotic resistance against other types of antibiotics such as:

Gentamicin

Levofloxacin

Ciprofloxacin

Streptomycin

Sadly, the majority of the strains of bacteria that have NDM-1 also have either plasmid or chromosomal resistance against these and other antibiotics. The term, 'super-bug,' is many times used loosely to describe organisms' resistance to usually 2 or more antibiotics. Bacteria that contain NDM-1 are often resistant to nearly every antibiotic; bacteria with NDM-1 have been termed a, 'super-bug,' and some researchers consider these bacteria to be the most dangerous super-bug of all that have developed to date.

Chart showing gram-negative bacteria found with NDM-1

While just discovered in the year 2009 and most likely because of genetic transfer of plasmids or other chromosomal segments, NDM-1 has been found in at least 4 different genera of gram-negative bacteria:

Klebsiella

Escherichia

Enterobacter

Acinetobacter

People in Pakistan, India, Canada, England, Australia, Sweden, America and Japan have been found to be infected with bacterial strains that produce NDM-1. Researchers speculate that the extremely quick spread of NDM-1 might be due to people seeking health care outside of their own country, such as visitors or travelers from India. Other researchers suggest the widespread, uncontrolled use of antibiotics favors the survival of NDM-1 containing bacterial strains. Another potential reason for the fast spread is that, 'Escherichia coli,' or, 'E. coli,' part of the usual bacteria found in the human intestine, easily exchanges plasmids. In fact - the first identified person infected with Klebsiella containing NDM-1 was also found to have an E. coli strain isolated from the feces with the capability of producing NDM-1.

Signs and Symptoms of Someone Infected with Bacteria Carrying NDM-1

The most predominate sign or symptom that a person is infected with bacteria carrying NDM-1 is the failure of antibiotic treatments, whether IV or oral, to improve the person's condition; particularly if the person is infected with a gram-negative bacterial type and is receiving treatment with an antibiotic that contains a beta-lactam ring structure. If the person has visited another country for elective surgery, or recently received treatment with antibiotics for an infection and returned to the United States or another industrialized nation with the infection, health care workers should be suspicious that bacteria producing NDM-1 might be causing the infection.

Due to the fact that NDM-1 may be carried by a number of types of gram-negative bacteria, the signs and symptoms of the diseases are of little or no assistance in distinguishing whether a person has an organism expressing the enzyme until antibiotic treatments have failed. Because gram-negative bacteria are known to cause a number of diseases such as:

Pneumonia

Urinary tract infections

Some wound infections

Gastrointestinal problems

People with these diseases that require antibiotic treatments and are not recovering as they should with treatments should have the gram-negative bacteria isolated and tested for antibiotic resistance.

Treatment for an Infection Caused by Bacteria that Make NDM-1

The best treatment for an infection caused by bacteria that make NDM-1 is to determine which antibiotics the NDM-1 strain is susceptible, yet not resistant to, and use those antibiotics for treatment of the person. One antibiotic - colistin, which is not used very often due to its toxicity, is often the only antibiotic NDM-1 producing bacteria are susceptible to. Some NDM-1 producing bacteria; however, have shown sensitivity to tigecycline and a few to aztreonam. These antibiotics; however, should not be used without first determining the resistance/susceptibility pattern for the individual infecting bacterial strain.

Antibiotic resistance/susceptibility patterns for bacteria are regularly done in labs that grow isolated bacterial strains in the presence of antibiotic-impregnated disks. Resistant bacteria grow up to the edge of the disk, while bacteria susceptible to being killed or inhibited by the antibiotic leave a clear space of no growth that extends away from the edge of the disk. The larger the clear space, the more susceptible the bacterial strain is to the antibiotic. Most NDM-1 producing bacteria show no clear space at all unfortunately. One issue with this test is that it takes around 2 days to achieve results.

Preventing Infections with Bacteria Containing NDM-1

Chart showing ways to help prevent infections with NDM-1

The chance of infections with bacteria containing NDM-1 may be reduced, or even prevented, by pretty simple hygienic methods that include:

Hand washing

Washing vegetables

Adequate treatment of water supplies

Avoiding areas and people known to harbor NDM-1-producing bacteria

The usual infection protective techniques available in hospitals should be used. People with NDM-1 bacteria should be treated like people with MRSA - with a private room and gloves, masks, and gowns made available for visitors and care providers. Unfortunately, there is no vaccine available for bacteria that produce NDM-1 and it is not likely one will be developed because so many bacterial strains might have the potential to produce NDM-1 if given the right genes.

Doctors and Researchers are Concerned about Bacteria with NDM-1

A number of health care workers and researchers are concerned about NDM-1 because it renders some of the most powerful and useful antibiotics ineffective. The antibiotics are often times the medications of choice for severe infections. Since the blaNDM-1 gene that produces the enzyme is often associated with other genes that code for other antibiotic resistance factors, they are concerned that resistance will be rapidly passed to most gram-negative bacteria and render a large group of bacteria resistant to most of the antibiotics currently in use.

While the spread is unlikely to be considered a pandemic like swine or bird flu, outbreaks of diseases caused by NDM-1 bacteria might result in high mortality. Researchers are also concerned that current antibiotic susceptibility tests often may take at least 2 days to complete - something that can be a long time for critically infected people who require treatment with antibiotics that might not have the ability to either inhibit or kill the bacteria they are infected with.

The field of research on NDM-1 is very active right now. It is hoped a number of developments in clinical diagnostic methods, antibiotic treatment plans, as well as antibiotics will arise in the near future. Sadly, the number of people infected with and carrying NDM-1 bacteria is expected to increase quickly. Researchers plan to attempt to stay a step ahead of these potentially dangerous antibiotic-resistant bacteria. Unfortunately, there is no guarantee of success. Prevention of infection remains the best defense against these bacteria.

Important:

• Disabled World uses cookies to help provide and enhance our services to you and tailor some content and advertising. By continuing you agree to the Disabled World Cookie Policy, Privacy Policy and Terms of Service.

• Disabled World is strictly a news and information website provided for general informational purpose only and does not constitute medical advice. Materials presented are in no way meant to be a substitute for professional medical care by a qualified practitioner, nor should they be construed as such. Any 3rd party offering or advertising on disabled-world.com does not constitute endorsement by Disabled World.